形式主语的问句
原形陈述句是It would do some good to tell them that.
To tell them that would do some good.
告诉他们那个有什么好处呢?
把那个告诉他们有什么用呢?
这里what是形容词,表示多么,形容good。what good would it do,这里的it是形势主语,to tell them that是真正主语。
那告诉他们这个事有什么好处?
Whar good would it do 是一个意群
that(是指那个代指的事情)